Efficient implementation of 90 degrees phase shifter in FPGA

In this article, we present an efficient way of implementing 90 phase shifter using Hilbert transformer with canonic signed digit (CSD) coefficients in FPGA. It is implemented using 27-tap symmetric finite impulse response (FIR) filter. Representing the filter coefficients by CSD eliminates the need for multipliers and the filter is implemented using shifters and adders/subtractors. The simulated results for the frequency response of the Hilbert transformer with infinite precision coefficients and CSD coefficients agree with each other. The proposed architecture requires less hardware as one adder is saved for the realization of every negative coefficient compared to convectional CSD FIR filter implementation. Also, it offers a high accuracy of phase shift

Evaluation of a discrete 4-PAM optical link for future automotive networks

A comparative study is presented between NRZ and 4-PAM to investigate the feasibility of Gigabit transmission in automotive optical networks. The system utilizes a SI-PCS fiber and an 850 nm VCSEL as transmitter. Laser driver and receiver are realized with discrete transistors at board level. Eye diagram measurements reveal that 4-PAM outperforms NRZ using 1m and 6m of fiber. Bitrates of 2 Gb/s are achieved at a BER ≤ 100000. Covering longer distances shows that SI-PCS introduces severe dispersion. Therefore, GI-PCS fiber is suggested as optical link for future automotive networks

High-speed driver and receiver electronics for next-generation optical networks

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Implementation of the dissection theorem in cadence virtuoso

This paper describes a tool for the Cadence Virtuoso software that implements the Dissection Theorem (DT) or General Network Theorem (GNT) and its applications: the Extra Element Theorem (EET), Chain Theorem (CT) and General Feedback Theorem (GFT). The tool allows a circuit designer to gain additional circuit insight by providing all second- and third-level transfer functions of the DT. In particular, feedback networks are factored into their exact components, enabling a deeper insight into the structure of the loop gain, direct forward transmission and hence closed-loop behaviour